1. Field of the Invention
This invention relates to an electric switch.
2. State of the Art
In customary switches of this kind the metal conductors are formed as planar surface segments of a sheet metal blank cut out by punching from the originally complete sheet metal. The metal conductors are at first still connected with one another by connecting webs so that the sheet metal blank can be embedded as a whole in a base plate of insulating material and, in the injection molding process of the base plate, the base plate is partially injection molded around the metal conductors. The connecting webs between the metal conductors are afterwards cleared away by purposefully drilling through the base plate and the connecting webs.
One or more bridging contacts are positioned in a guiding and actuating device by means of which they can be moved along the associated metal conductors. Thereby the bridging contacts rest against the metal conductors under the effect of pressure springs.
In dependence on the desired switching operations two of the metal conductors extending in parallel to each other and over which a bridging contact is jointly moved are either interrupted both or only one in particular places, so that, with precision, two or more metal conductors partially having different lengths are located behind one another. In the transitional places between two of these metal conductors located one behind the other either the space between them is filled with insulating material of the base plate up to the level of the metal conductors or there is a gap between them.
The bridging contacts are mostly punched out from sheet metal blanks. Sometimes they are additionally bent. If considerable production tolerances appear on the guiding and operating device for the bridging contact and/or on the base plate including the metal conductors generally produced as injection molded parts, for example, the surface of the base plate reaches the same level as the surface of one of the metal conductors or is even slightly higher so that the electric switching properties of such a switch are heavily impaired. When in a transitional plate the space between the metal conductors is filled with insulating material, the bridging contact can more easily glide over the transitional place. However, then it is a risk that in the process of injection molding around the metal conductors insulating material may be brought onto the metal conductor causing difficulties in making contact later on, for example, a delayed switch contact or a premature interruption of the contact. If, in the transitional places of the metal conductors, a gap is formed by an appropriate molding, undesired insulating material will not impede the making of contact. However, the risk of a deteriorated gliding behavior of the bridging contact may come into existence and the course of motion in the transitional places may be more or less impeded.